Have you read the independent report? The point of the report was that their engineering practices (both software and hardware) were so extraordinarily dangerous, the ECU was impossible to test with any authority. Its behavior was effectively non-deterministic in many of their cars from that era.
That's sort of the point. I'm not defending their code. I'm pointing out that even if the code were immaculate, it would be hard for an code auditing firm to say "this has no sudden acceleration bugs". It's a very CYA statement.
